Field of the Invention
The present invention relates to an image processing apparatus such as a digital still camera and digital video camera capable of movie recording, a control method therefor, and a storage medium.
Description of the Related Art
For an image processing apparatus such as a digital still camera capable of movie recording, techniques to switch a frame rate in accordance with changes in luminance are known. For example, an image pickup device that detects the luminance level of an image acquired from a CMOS or CCD image pickup device, compares this luminance level with a preset threshold value, and increases or decreases the frame rate if determining the need of switching a frame rate, is known (Japanese Laid-Open Patent Publication (Kokai) No. 2003-87630).
In addition, techniques to adjust image pickup conditions in accordance with the state of a subject in movie recording in order to continually maintain AE (automatic exposure) and AWB (auto white balance) suitable for the state of the subject, is known (Japanese Laid-Open Patent Publication (Kokai) No. 2012-151706).
These techniques enable performing movie recording while changing a frame rate such that the movie recording can be performed while continually maintaining the conditions of the AE and AWB suitable for the state of the subject.
However, in the above-described Japanese Laid-Open Patent Publication (Kokai) No. 2003-87630 and Japanese Laid-Open Patent Publication (Kokai) No. 2012-151706, the frame rate in the movie recording has to be changed in accordance with various conditions of a subject, and thus it is difficult to deal with the condition that the movie recording is performed at a fixed frame rate. In addition, when the movie recording is performed at a fixed frame rate, a subject having a low luminance raises a problem in that evaluation values of AF (autofocus), AE, AWB, and the like cannot be correctly acquired because of a fixed upper limit of an exposure time for the subject.